custom view (component)

- sample source

http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/view/LabelView.html



- 상속

public class LabelView extends View


- view init

private final void initLabelView() {
        mTextPaint = new Paint();
        mTextPaint.setAntiAlias(true);
        mTextPaint.setTextSize(16);
        mTextPaint.setColor(0xFF000000);
        setPadding(3, 3, 3, 3);
    }


- draw

@Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawText(mText, getPaddingLeft(), getPaddingTop() - mAscent, mTextPaint);
    }


- measure

/**
     * @see android.view.View#measure(int, int)
     */
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        setMeasuredDimension(measureWidth(widthMeasureSpec),
                measureHeight(heightMeasureSpec));
    }

    /**
     * Determines the width of this view
     * @param measureSpec A measureSpec packed into an int
     * @return The width of the view, honoring constraints from measureSpec
     */
    private int measureWidth(int measureSpec) {
        int result = 0;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        if (specMode == MeasureSpec.EXACTLY) {
            // We were told how big to be
            result = specSize;
        } else {
            // Measure the text
            result = (int) mTextPaint.measureText(mText) + getPaddingLeft()
                    + getPaddingRight();
            if (specMode == MeasureSpec.AT_MOST) {
                // Respect AT_MOST value if that was what is called for by measureSpec
                result = Math.min(result, specSize);
            }
        }

        return result;
    }

    /**
     * Determines the height of this view
     * @param measureSpec A measureSpec packed into an int
     * @return The height of the view, honoring constraints from measureSpec
     */
    private int measureHeight(int measureSpec) {
        int result = 0;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        mAscent = (int) mTextPaint.ascent();
        if (specMode == MeasureSpec.EXACTLY) {
            // We were told how big to be
            result = specSize;
        } else {
            // Measure the text (beware: ascent is a negative number)
            result = (int) (-mAscent + mTextPaint.descent()) + getPaddingTop()
                    + getPaddingBottom();
            if (specMode == MeasureSpec.AT_MOST) {
                // Respect AT_MOST value if that was what is called for by measureSpec
                result = Math.min(result, specSize);
            }
        }
        return result;
    }